There are many applications in which it is highly desirable to center an elongated object within a body fitted around the object. One specific example is found in wire rope testing devices which include a magnetic testing head through which the wire rope is passed. For purposes of maximizing testing results, the wire rope should be substantially centered within the test head. This centering can present problems particularly in view of the fact that wire ropes come in numerous different diameter sizes.
In the past the centering of different diameter sizes of wire ropes has been achieved by providing a plurality of sleeves of different thicknesses to be used with the magnetic testing head. According to this system a relatively thick wire rope is centered by using a thin sleeve whereas a relatively thin wire rope is centered using a thicker sleeve.
The problem encountered with this interchangeable sleeve centering method are two fold. Firstly the system necessitates the requirement for manufacturing many different thicknesses of sleeves for the many different sizes of wire ropes. Secondly the multi-sleeve system substantially reduces the portability of the test head simply from the fact that the person testing these wire ropes must at the same time be carrying a plurality of testing sleeves which are both bulky and relatively heavy. Both the bulk and the weight are substantial problems in that much of the wire rope testing is done directly in the field.